From 927bb2547a6024508d23392411256b10be53e205 Mon Sep 17 00:00:00 2001
From: Roland Schilter <roli@weave.works>
Date: Wed, 21 Jun 2017 16:27:04 +0200
Subject: [PATCH] Honor DOCKER_* env variables in probe and app

Changed default for flag `-app.docker` to use the DOCKER_* env variables
instead of hardcoded /var/run/docker.sock; uses docker's default if
no DOCKER_HOST defined, for both probe and app.

Fixes #1975
---
 app/weave.go             | 7 +++----
 probe/docker/registry.go | 3 +++
 probe/overlay/weave.go   | 3 +++
 prog/main.go             | 4 ++--
 prog/probe.go            | 4 +---
 5 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/app/weave.go b/app/weave.go
index 7ea3711700..fb7fe35a99 100644
--- a/app/weave.go
+++ b/app/weave.go
@@ -12,10 +12,9 @@ import (
 
 // Default values for weave app integration
 const (
-	DefaultHostname       = "scope.weave.local."
-	DefaultWeaveURL       = "http://127.0.0.1:6784"
-	DefaultContainerName  = "weavescope"
-	DefaultDockerEndpoint = "unix:///var/run/docker.sock"
+	DefaultHostname      = "scope.weave.local."
+	DefaultWeaveURL      = "http://127.0.0.1:6784"
+	DefaultContainerName = "weavescope"
 )
 
 // WeavePublisher is a thing which periodically registers this app with WeaveDNS.
diff --git a/probe/docker/registry.go b/probe/docker/registry.go
index 1082def1c1..223b115759 100644
--- a/probe/docker/registry.go
+++ b/probe/docker/registry.go
@@ -92,6 +92,9 @@ type Client interface {
 }
 
 func newDockerClient(endpoint string) (Client, error) {
+	if endpoint == "" {
+		return docker_client.NewClientFromEnv()
+	}
 	return docker_client.NewClient(endpoint)
 }
 
diff --git a/probe/overlay/weave.go b/probe/overlay/weave.go
index b87cb88eb6..19eca7d22c 100644
--- a/probe/overlay/weave.go
+++ b/probe/overlay/weave.go
@@ -153,6 +153,9 @@ type DockerClient interface {
 }
 
 func newDockerClient(endpoint string) (DockerClient, error) {
+	if endpoint == "" {
+		return docker_client.NewClientFromEnv()
+	}
 	return docker_client.NewClient(endpoint)
 }
 
diff --git a/prog/main.go b/prog/main.go
index c1578ad83f..ecb9d3d30b 100644
--- a/prog/main.go
+++ b/prog/main.go
@@ -337,7 +337,7 @@ func setupFlags(flags *flags) {
 	flag.StringVar(&flags.app.weaveAddr, "app.weave.addr", app.DefaultWeaveURL, "Address on which to contact WeaveDNS")
 	flag.StringVar(&flags.app.weaveHostname, "app.weave.hostname", "", "Hostname to advertise in WeaveDNS")
 	flag.StringVar(&flags.app.containerName, "app.container.name", app.DefaultContainerName, "Name of this container (to lookup container ID)")
-	flag.StringVar(&flags.app.dockerEndpoint, "app.docker", app.DefaultDockerEndpoint, "Location of docker endpoint (to lookup container ID)")
+	flag.StringVar(&flags.app.dockerEndpoint, "app.docker", "", "Overwrite location of docker endpoint (to lookup container ID) (default \"$DOCKER_HOST\")")
 	flag.Var(&flags.containerLabelFilterFlags, "app.container-label-filter", "Add container label-based view filter, specified as title:label. Multiple flags are accepted. Example: --app.container-label-filter='Database Containers:role=db'")
 	flag.Var(&flags.containerLabelFilterFlagsExclude, "app.container-label-filter-exclude", "Add container label-based view filter that excludes containers with the given label, specified as title:label. Multiple flags are accepted. Example: --app.container-label-filter-exclude='Database Containers:role=db'")
 
@@ -394,7 +394,7 @@ func main() {
 	if flags.probe.httpListen != "" {
 		_, _, err := net.SplitHostPort(flags.probe.httpListen)
 		if err != nil {
-			log.Fatalf("Invalid value for -app.http.address: %v", err)
+			log.Fatalf("Invalid value for -probe.http.address: %v", err)
 		}
 	}
 
diff --git a/prog/probe.go b/prog/probe.go
index 1fe6d95e57..cbe544d5a3 100644
--- a/prog/probe.go
+++ b/prog/probe.go
@@ -42,7 +42,6 @@ const (
 
 var (
 	pluginAPIVersion = "1"
-	dockerEndpoint   = "unix:///var/run/docker.sock"
 )
 
 func checkNewScopeVersion(flags probeFlags) {
@@ -199,7 +198,6 @@ func probeMain(flags probeFlags, targets []appclient.Target) {
 			CollectStats:           true,
 			HostID:                 hostID,
 			HandlerRegistry:        handlerRegistry,
-			DockerEndpoint:         dockerEndpoint,
 			NoCommandLineArguments: flags.noCommandLineArguments,
 			NoEnvironmentVariables: flags.noEnvironmentVariables,
 		}
@@ -236,7 +234,7 @@ func probeMain(flags probeFlags, targets []appclient.Target) {
 
 	if flags.weaveEnabled {
 		client := weave.NewClient(sanitize.URL("http://", 6784, "")(flags.weaveAddr))
-		weave, err := overlay.NewWeave(hostID, client, dockerEndpoint)
+		weave, err := overlay.NewWeave(hostID, client, "")
 		if err != nil {
 			log.Errorf("Weave: failed to start client: %v", err)
 		} else {